Extensible markup language (XML) is increasingly becoming the preferred format for transferring information. XML is a tag-based hierarchical language that is extremely rich in terms of the information that it can be used to represent. For example, XML can be used to represent information spanning the spectrum from semi-structured information (such as one would find in a word processing document) to generally structured information (such as that which is contained in a table). XML is well-suited for many types of communication including business-to-business and client-to-server communication. For more information on XML, XSLT, and XSD (schemas), the reader is referred to the following documents which are the work of, and available from the W3C (World Wide Web consortium): XML 1.0 second edition specification; XSL Transformations (XSLT) Version 1.0; XML Schema Part 1: Structures; and XML Schema Part 2: Datatypes.
Before information can be transferred, however, it must first be collected. To collect information from a user, an XML data file usually is transformed into a viewable, editable form. This form, called a rendered form, is created by applying a transformation file on the XML data file. This rendered form is typically written in HTML (HyperText Machine Language) or eXtensible HTML (XHTML), and is designed to allow a user to enter data into data-entry fields that map to locations in the XML data file. Thus, the user can enter data into a particular data-entry field and that data will be stored in a particular part (or “node”) of the XML data file.
A transformation file used to transform the XML data file into a rendered form is typically written in XSLT. Applying an XSLT transformation file on an XML data file generates an XHTML rendering file, which, when executed, generates a rendered form.
One of the problems with rendered forms is that, as a user edits the XML data file by editing the XHTML rendered form, the form does not reflect all changes to the data file. Even though the data entered into a data-entry field in the form may appear in that data-entry field (though this is typically done through means other than transforming the data file by applying a transformation file), this to input often affects other parts of the data file and how that data file should be rendered in a rendered form.
By way of example, a XSLT transformation file can be applied on the XML data file and, by so doing, change nodes of the data file other than the node into which data was input. Applying an XSLT transformation file on an XML data file can even change the structure of the data file. Also, by applying the transformation file on the data file, the transformation file may need to access databases to find data to use in computations or to input into a node of the data file, such as a function whereby when a zip code is entered into a data-entry field. Here, transforming the data file by applying the transformation file fills in other nodes of the data file (and thus also the data-entry fields of the rendered form) for the city and state corresponding to the zip code.
The rendered form does not reflect these changes to the data file because XSLT transformations are one-way. In other words, applying an XSLT transformation file to an XML data file creates a rendered form, but as the XML data file changes, the rendered form does not. Thus, the rendered form can be out-of-date with how the data file should be when the data file receives a new input.
To give the user an up-to-date rendered form, the XSLT transformation can be reapplied to the XML data file after each change made to the data file. The result of such a full transformation is a full rendering file, from which a new rendered form can be created. By so doing, the user sees an accurate rendering (sometimes called a “view”) of the current state of the XML data file.
One problem with this, however, is that applying an XSLT transformation to an XML data file can be slow and require extensive computer resources.
Further, while this full transformation can be slow, executing the result of this transformation (a full rendering file), can also take extensive time and resources.
Because of the amount of time and resources required to transform the XML data file and render a full rendering file into a rendered form, a user often cannot efficiently view changes to an XML data file in the rendered form while editing the rendered form. With each edit made by the user, the user has to wait for a new rendered form to be created. Transforming an XML data file to create a new rendering file and then executing the rendering file into a rendered form can take many seconds. Having to wait this long each time the user makes a change inhibits the user from quickly and easily editing an XML data file through a rendered form of that XML data file.